Expansion of Product_{k>=1} (1 - x^k)^(sigma_2(k)).

Terms

a(0) =1a(1) =-1a(2) =-5a(3) =-5a(4) =-1a(5) =35a(6) =66a(7) =100a(8) =15a(9) =-330a(10) =-841a(11) =-1591a(12) =-1468a(13) =426a(14) =6306a(15) =16399a(16) =27745a(17) =31544a(18) =6364a(19) =-70389a(20) =-225322a(21) =-435265a(22) =-617937a(23) =-537135a(24) =176008a(25) =1970213a(26) =5150080a(27) =9277624a(28) =12631298a(29) =11048049